Rotary controls for electrical instruments and other equipment have generally been designed either to be continuously variable or to have a single set of rotational stop positions provided by permanent detents. These controls are dedicated to a single function which is best carried out either in discrete steps or continuously.
Sophisticated instruments such as the current generation of oscilloscopes, however, now offer the operator the ability to select among several functions for a rotary control. It is desirable, therefore, to provide for such instruments a rotary control suitable for different functions, one that is both continuously variable and has one or more selectable detents. Each detent can provide a different set of predetermined rotational stop positions that correspond to a different control function or to different gradations of the same function. The continuously variable feature can permit the control to be adjusted to an arbitrary position.
Rotary controls are known to exist that have two rotary components, one component having detents and the other being continuously variable for fine tuning. But a single rotary control that combines both features is not known to exist.